Electrostatic control of metal wetting layers during deposition

Abstract

There is disclosed a system for the electrostatic control of a metal wetting layer during deposition and a method of electrostatically controlling a metal wetting layer during deposition using a deposition system. In one example, control of the metal wetting layer is provided by changing or applying an electrostatic field acting on a deposited material or acting on a substrate on which a material is deposited. In another example, control is of the thickness of the metal wetting layer. In another example, control is of the presence or absence of the metal wetting layer. The metal wetting layer can be a liquid metal or liquid metal alloy, for example the metal wetting layer could be Boron, Aluminium, Indium, Gallium or Thallium. In another example, control is of the thickness, or presence, of a Gallium wetting layer during GaN film growth.

What is claimed is: 
     
         1 . A method of electrostatically controlling a metal wetting layer during deposition of a material in a remote plasma enhanced chemical vapor deposition reactor comprising a plasma creation region for creating a plasma and a reaction region for deposition of the material, the method comprising:
 electrically biasing a grid positioned above a substrate on which the material is deposited, the substrate positioned in the reaction region of the remote plasma enhanced chemical vapor deposition reactor that is downstream of the plasma, and the grid also positioned in the reaction region of the remote plasma enhanced chemical vapor deposition reactor that is downstream of the plasma; and,   controlling a root mean square surface roughness of the metal wetting layer using an electrostatic field produced by biasing the grid.   
     
     
         2 . The method of  claim 1 , wherein the substrate is isolated by the grid from the electric field of the plasma. 
     
     
         3 . The method of  claim 1 , wherein the grid is negatively biased relative to a plasma potential of the plasma. 
     
     
         4 . The method of  claim 1 , wherein the grid is negatively biased relative to ground. 
     
     
         5 . The method of  claim 1 , wherein the grid is negatively biased relative to an electric potential of the substrate. 
     
     
         6 . The method of  claim 5 , wherein a metalorganic is directed towards the substrate, and the negative bias of the grid reduces hydrocarbon in the material that is deposited. 
     
     
         7 . The method of  claim 5 , wherein a metalorganic is directed towards the substrate, and the negative bias of the grid reduces carbon in the material that is deposited. 
     
     
         8 . The method of  claim 5 , wherein a metalorganic is directed towards the substrate, and the negative bias of the grid removes at least some residual methyl groups during decomposition of the metalorganic. 
     
     
         9 . The method of  claim 8 , wherein the metalorganic is trimethylgallium. 
     
     
         10 . The method of  claim 1 , wherein the material is a Group III nitride. 
     
     
         11 . The method of  claim 1 , wherein the material is GaN. 
     
     
         12 . The method of  claim 1 , wherein the grid is negatively biased between −20 V to −200 V. 
     
     
         13 . The method of  claim 1 , wherein the root mean square surface roughness is between 0.374 and 24.5 nm. 
     
     
         14 . The method of  claim 1 , further including controlling a thickness of the metal wetting layer using the electrostatic field produced by biasing the grid. 
     
     
         15 . The method of  claim 1 , wherein the remote plasma enhanced chemical vapor deposition reactor is an Atomic Layer Deposition reactor. 
     
     
         16 . The method of  claim 1 , wherein the remote plasma enhanced chemical vapor deposition reactor is a pulsed reactor. 
     
     
         17 . A method of electrostatically controlling a metal wetting layer during deposition of a material in a remote plasma enhanced chemical vapor deposition reactor comprising a plasma creation region for creating a plasma and a reaction region for deposition of the material, the method comprising:
 electrically negatively biasing a grid relative to an electric potential of a substrate, the grid positioned above the substrate on which the material is deposited, the substrate positioned in the reaction region that is downstream of the plasma, and the grid positioned in the reaction region that is downstream of the plasma; and,   directing a metalorganic towards the substrate;   wherein negatively biasing the grid reduces an amount of carbon in the material during deposition compared to an amount of carbon in the material during deposition without negatively biasing the grid.   
     
     
         18 . A remote plasma enhanced chemical vapor deposition reactor for electrostatic control of a metal wetting layer during deposition of a material, comprising:
 a plasma creation region for creating a plasma;   a reaction region for deposition of the material that is downstream of the plasma;   a substrate on which the material is deposited, the substrate positioned in the reaction region;   a grid for producing an electrostatic field able to act on the material that is deposited on the substrate by electrically biasing the grid relative to the substrate, the grid positioned above the substrate and the grid positioned in the reaction region; and,   a hollow cathode positioned in the plasma creation region;   wherein the grid is positioned closer to the substrate than to the hollow cathode.   
     
     
         19 . The reactor of  claim 18 , wherein the grid is positioned between 10 mm to 100 mm away from the substrate. 
     
     
         20 . The reactor of  claim 18 , wherein the grid is positioned between 10 mm to 50 mm away from the substrate.